DE60014622T2 - PROCESS FOR THE PREPARATION OF ALKYLAROMATES - Google Patents

Abstract

The present invention provides a process for producing a monoalkylated aromatic compound, particularly ethylbenzene or cumene, in which a polyalkylated aromatic compound is contacted with an alkylatable aromatic compound in the liquid phase and in the presence of a transalkylation catalyst comprising TEA-mordenite having an average crystal size of less than 0.5 micron.

Description

BACKGROUND THE INVENTION

The The present invention relates to a process for the preparation of Alkylaromatics, in particular ethylbenzene and cumene.

ethylbenzene and cumene are valuable commodity chemicals that are industrially used for manufacturing be used by styrene monomer or phenol. ethylbenzene Can be made with a variety of different chemical processes become; a process that, however, has a significant commercial success has reached is the vapor phase alkylation of benzene with ethylene in the presence of a solid, acidic ZSM-5 zeolite catalyst. In commercial operation of this process, the polyalkylated Benzenes, including both polymethylated and polyethylated benzenes, which are inherently together with ethylbenzene in the alkylation reactor, with Benzene transalkylated to additional Produce ethylbenzene that either returns to the alkylation reactor guided or fed to a separate transalkylation reactor. examples for such ethylbenzene manufacturing processes are disclosed in US-A-3,751,504, US-A-4 547 605 and US-A-4 016 218.

In Attention has recently been paid to liquid phase processes for production directed by ethylbenzene from benzene and ethylene, because liquid phase method operated at a lower temperature than their vapor-phase analogs and therefore tend to lower by-product yields respectively. For example, US-A-4,891,458 describes liquid phase synthesis of ethylbenzene with zeolite β, while US-A-5,334,795 discloses the use of MCM-22 in liquid phase synthesis of ethylbenzene.

cumene has been commercially available for many years by the liquid phase alkylation of benzene with propylene over a Friedel-Crafts catalyst, in particular solid phosphoric acid or Aluminum chloride, manufactured. Lately, however, have become Zeolite-based catalyst systems as active and selective for propylation from benzene to cumene. For example, that describes US-A-4 992 606 discloses the use of MCM-22 in liquid phase alkylation of benzene with propylene.

The US-A-5 453 554 describes a process for the preparation of aromatic Short chain alkyl compounds such as cumene and ethylbenzene, by contacting at least one alkylatable aromatic Compound, such as benzene, with an alkylating agent of 1 to 5 Carbon atoms in the presence of MCM-56. The procedure can either in the liquid or in the vapor phase, and polyalkylated by-products can by transalkylation in the alkylation reactor or in a separate reactor in additional be converted monoalkylated product. According to US Pat. No. 5,453,554, the transalkylation catalyst MCM-49, MCM-22, PSH-3, SSZ-25, zeolite X, zeolite Y, zeolite β or mordenite. Certain in US-A-5,453,554 are suitable transalkylation catalysts cited forms of mordenite are acid-dealuminated mordenite, as disclosed in US-A-5,243,116, and TEA-mordenite as disclosed in US-A-3,766,093 and US Pat US-A-3,894,104. Although US-A-3,766,093 and US-A-3 894 104 re the crystal size of there produced TEA mordenite reveal nothing, has a repeat Examples of these patents show that the mordenite product especially large Crystals with a size of more than 1 μm and typically around 5 to 10 microns is.

One in liquid phase method for the production of alkylaromatics, such as cumene and ethylbenzene, existing Problem is that their lower operating temperature the activity requirements of the catalyst, especially in the transalkylation step, and It was an object of the present invention to provide an aromatic transalkylation catalyst with elevated activity provide.

Especially was now unexpectedly found to be through production of TEA mordenite with a controlled small crystal size of less than 0.5 μm possible is a catalyst with significantly improved liquid phase aromatic transalkylation activity manufacture.

SUMMARY THE INVENTION

According to one aspect of the invention, there is provided a process for preparing a monoalkylated aromatic compound comprising reacting a polyalkylated aromatic compound in the liquid phase and in the presence of TEA-mordenite having an average crystal size of less than 0.5 μm transalkylation catalyst with an alkylatable catalyst contacted aromatic compound to produce a monoalkylated aromatic compound.

Preferably have the alkyl groups of the polyalkylated aromatic compound 1 to 5 carbon atoms.

• (a) eine alkylierbare aromatische Verbindung in der Gegenwart von Alkylierungskatalysator mit einem Alkylierungsmittel in Kontakt gebracht wird, um ein die monoalkylierte aromatische Verbindung und eine polyalkylierte aromatische Verbindung umfassendes Produkt bereitzustellen, und dann
• (b) die polyalkylierte aromatische Verbindung aus Schritt (a) in der flüssigen Phase und in der Gegenwart von TEA-Mordenit mit einer durchschnittlichen Kristallgröße von weniger als 0,5 μm umfassendem Transalkylierungskatalysator mit der alkylierbaren aromatischen Verbindung in Kontakt gebracht wird, um eine monoalkylierte aromatische Verbindung herzustellen.

In a further aspect, the invention consists in a process for the preparation of a monoalkylated aromatic compound, in which:

• (a) contacting an alkylatable aromatic compound in the presence of alkylating catalyst with an alkylating agent to provide a product comprising the monoalkylated aromatic compound and a polyalkylated aromatic compound, and then
• (b) contacting the polyalkylated aromatic compound from step (a) in the liquid phase and in the presence of TEA mordenite with an average crystal size of less than 0.5 μm transalkylation catalyst with the alkylatable aromatic compound to form a monoalkylated to produce aromatic compound.

Preferably the alkylation step (a) is carried out in the liquid phase.

Preferably includes the alkylating agent is an alkylating aliphatic group 1 to 5 carbon atoms.

Preferably the alkylating agent is ethylene or propylene, and the alkylating agent aromatic compound is benzene.

Preferably For example, the alkylation catalyst of step (a) is selected from MCM-22, MCM-49, MCM-56 and zeolite β.

DETAILED DESCRIPTION OF THE INVENTION

The The present invention relates to a process for the preparation of a monoalkylated aromatic compound, preferably ethylbenzene and cumene, by liquid phase transalkylation the polyalkylated derivative with an alkylatable compound, preferably benzene. More preferably, the invention deals with a method wherein the liquid phase transalkylation step followed by an alkylation step, which is also in the liquid phase carried out and wherein the alkylatable compound with an alkylating agent is reacted, preferably ethylene and propylene, to the required monoalkylated aromatic end product and the polyalkylated derivative prepared, separated and in the transalkylation step is fed.

Of the Term "aromatic" with reference to the alkylatable compounds useful herein are to be used in accordance with his be understood in the art accepted scope, the alkyl-substituted and unsubstituted mono- and polynuclear compounds. One Heteroatom-containing compounds having an aromatic character are with the proviso also useful that they are under the chosen reaction conditions do not act as catalyst poisons.

substituted Aromatic compounds that can be alkylated here must be at least have a hydrogen atom bonded directly to the aromatic nucleus. The aromatic rings can with one or more alkyl, aryl, alkaryl, alkoxy, aryloxy, Be substituted by cycloalkyl, halide and / or other groups, which do not interfere with the alkylation reaction.

suitable aromatic hydrocarbons include benzene, naphthalene, anthracene, Naphthacene, perylene, coronene and phenanthrene, with benzene being preferred is.

in the Generally, the alkyl groups containing as substituents of the aromatic compound may be present, from 1 to 22 carbon atoms and usually 1 to 8 carbon atoms, more common 1 to 4 carbon atoms.

Suitable alkyl-substituted aromatic compounds include toluene, xylene, isopropylbenzene, n-propylbenzene, α-methylnaphthalene, ethylenebenzene, cumene, mesitylene, durene, p-cymene, butylbenzene, pseudocumene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, isoamylbenzene, isohexylbenzene , Pentaethylbenzene, pentamethylbenzene, 1,2,3,4-tetraethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4-triethylbenzene, 1,2,3-trimethylbenzene, m-butyltoluene, p-butyltoluene, 3 , 5-diethyltoluene, o-ethyltoluene, p-ethyltoluene, m-propyltoluene, 4-ethyl-m-xylene, dimethylnaphthalenes, ethylnaphthalene, 2,3-dimethylanthracene, 9-ethylanthracene, 2-methylanthracene, o-methylanthracene, 9,10-dimethylphenanthrenes and 3-methylphenanthrene. Higher molecular weight alkyl aromatic hydrocarbons may also be used as starting materials and include aromatic hydrocarbons, such as those prepared by the alkylation of aromatic hydrocarbons with olefin oligomers. Such a product is often referred to in the art as alkylate and includes hexylbenzene, nonylbenzene, dodecylbenzene, pentadecylbenzene, hexyltoluene, nonyltoluene, dodecyltoluene and pentadecyltoluene. Alkylate is very often obtained as a high-boiling fraction in which the alkyl group bound to the aromatic nucleus varies in size from C ₆ to C ₁₂ . When cumene or ethylbenzene is the desired product, the present process produces acceptably few by-products such as xylenes. The xylene production in such cases may be less than 500 ppm.

basics Amounts of benzene, toluene and / or xylene containing reformate provides a particularly useful feedstock for the alkylation process of the invention represents.

The in the method according to the invention useful alkylating agents generally include any aliphatic or aromatic organic compound with one or several available alkylating aliphatic groups that react with the alkylatable aromatic compound capable or are, wherein the alkylating group is preferably from 1 to 5 carbon atoms has. Examples of suitable Alkylating agents are olefins such as ethylene, propylene, the butenes and the pentenes, alcohols (including monoalcohols, dialcohols and trialcohols) such as methanol, ethanol, the propanols, the butanols and the pentanols, aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, Butylaldehyde and n-valeraldehyde, and alkyl halides, such as methyl chloride, ethyl chloride, the propyl chlorides, the butyl chlorides and the pentyl chlorides.

mixtures of light olefins are in the alkylation process according to the invention as Alkylating agent particularly useful. Corresponding are mixtures of ethylene, propylene, butenes and / or pentenes, the main constituents a variety of refinery streams are, for. As fuel gas, ethylene, propylene, etc. containing exhaust gas a gas plant, lightweight olefin-containing exhaust gas of a naphtha cracker, FCC (fluid catalytic crackers), propane / propylene refinery streams, etc. useful as alkylating agent here. For example, own one typical light FCC olefin stream has the following composition:

Out the method according to the invention available Close reaction products Ethylbenzene from the reaction of benzene with ethylene, cumene from the Reaction of benzene with propylene, ethyltoluene from the reaction of Toluene with ethylene, Cymole from the reaction of toluene with propylene and sec-butylbenzene from the reaction of benzene with n-butenes.

The alkylation process according to the invention is carried out so that the organic reactants, that is the alkylatable aromatic compound and the alkylating agent, in a suitable reaction zone, for. In a flow reactor containing a fixed bed of the catalyst composition, under effective alkylation conditions with an alkylation catalyst. Such conditions include a temperature of 0 ° C to 500 ° C, and preferably from 50 ° C to 250 ° C, a pressure of 20 to 25,331 kPa, and preferably 507 to 10,133 kPa, a molar ratio of alkylatable aro matic compound to alkylating agent of 0.1: 1 to 50: 1 and preferably 0.5: 1 to 10: 1 and an hourly space velocity (WHSV) of 0.1 to 500 h ^-1 , preferably 0 , 5 to 100 h ^-1 .

The Reactants can either in the vapor phase or in the liquid phase and can be undiluted, this means free from intentional mixing or dilution with other materials be, or you can with the support of carrier gases or diluents, such as hydrogen or nitrogen, with the zeolite catalyst composition be brought into contact.

If Benzene is alkylated with ethylene to produce ethylbenzene, For example, the alkylation reaction can be carried out in the liquid phase. Suitable liquid phase conditions shut down a temperature of 150 ° C up to 316 ° C, preferably from 205 ° C up to 260 ° C, a pressure of up to 20,875 kPa, preferably from 2,860 to 5,600 kPa, a throughput of 0.1 to 20 WHSV, preferably 1 to 6 WHSV, based on the ethylene feed, and a molar ratio of Benzene to the ethylene in the alkylation reactor from 1: 1 to 30 : 1, preferably from 1: 1 to 10: 1.

When benzene is alkylated with propylene to produce cumene, the reaction may also take place under liquid phase conditions, including a temperature up to 250 ° C, eg up to 150 ° C, eg from 10 ° C to 125 ° C, a pressure of 25,331 kPa or less, eg 101 to 3040 kPa, and an hourly mass flow rate (WHSV) of aromatic hydrocarbon from 5 h ^-1 to 250 h ^-1 , preferably from 5 h ^-1 to 50 h ^-1 .

Of the Alkylation catalyst is a crystalline molecular sieve and preferably selected from MCM-22 (described in detail in US-A-4,954,325), MCM-49 (described in detail in US Pat. No. 5,236,575), MCM-56 (in detail in US-A-5,362,697) and zeolite β (described in detail in US-A-3,308 069 described). The molecular sieve can also be used on conventional Way combined with an oxide binder, such as alumina, so be that the Endalkylierungskatalysator 2 to 80 wt .-% sieve contains.

Of the Alkylierungsreaktorabstrom contains the excess aromatic Feedstock, monoalkylated product, polyalkylated products and various impurities. The aromatic feedstock is recovered by distillation and recycled to the alkylation reactor. Usually, a lower Outflow from the recycle stream taken to non-reactive impurities from the circulation too eliminate. The bottoms from the baltic distillation are further distilled to monoalkylated product of polyalkylated Products and other heavy materials.

The separated from the Alkylierungsreaktorabstrom polyalkylated Products are transformed into a transalkylation reactor via a suitable transalkylation catalyst with additional aromatic feedstock implemented. According to the invention Transalkylation a certain, small crystalline form from TEA-mordenite, that is one from a tetraethylammonium control agent synthetic reaction mixture prepared synthetic mordenite. TEA mordenite is disclosed in US-A-3,766,093 and US-A-3,894,104, As shown in the following examples, those disclosed in these patents but described for the production of from above all big ones Crystals with a size of more than 1 μm and typically composed by 5 to 10 microns Mordenitprodukt. It has now been found that a control of Synthesis, so that the obtained TEA-mordenite an average Crystal size of less than 0.5 μm has, to a catalyst with significantly increased activity for the liquid phase aromatic transalkylation leads.

Of the necessary small-crystalline TEA-mordenite can be obtained by crystallization from a synthesis mixture with a molar composition within the following areas are produced.

The crystallization is carried out at a temperature of 90 to 200 ° C for a period of 6 to 180 hours the performed. The resulting TEA mordenite may be combined in a conventional manner with an oxide binder such as alumina such that the final transalkylation catalyst contains from 2 to 80% by weight sieve.

The Transalkylation reaction according to the invention will be in the liquid Phase under suitable conditions so that the polyalklyated Aromatics with the additional aromatic feed react to additional monoalkylated product manufacture. Suitable transalkylation conditions include Temperature from 100 to 260 ° C, a pressure of 1,000 to 5,000 kPa, an hourly mass flow rate of 1 to 10, based on total feedstock, and a benzene / polyalkylated one Benzene-weight ratio from 1: 1 to 6: 1.

If the polyalkylated aromatics are polyethylbenzenes and with benzene be reacted to produce ethylbenzene include the Transalkylation conditions preferably a temperature of 220 to 260 ° C, a pressure of 2,000 to 3,000 kPa, an hourly mass flow rate of 2 to 6, based on total feedstock, and a benzene / polyethylbenzenes (PEB) weight ratio from 2: 1 to 6: 1.

If the polyalkylated aromatics are polypropylbenzenes and with benzene reacted to produce cumene, close the transalkylation conditions preferably a temperature of 100 to 200 ° C, a pressure of 2,000 to 3,000 kPa, an hourly Mass flow rate from 1 to 10, based on total feed material, and a benzene / polyisopropylbenzene (PIPB) weight ratio of 1: 1 to 6: 1.

Of the Downstream from the transalkylation reactor is effluent with alkylation reactor mixed and the combined stream distilled to the desired monoalkylated To separate product.

The The invention will be described with reference to the following examples.

example 1

A synthesis mixture comprising water, precipitated silica, aluminum sulphate solution, sodium hydroxide and tetraethylammonium bromide and having the following molar composition (based on aluminum oxide = 1) was prepared: silica = 39.7 Na ₂ O = 7.3 SO ₄ ^2- = 2.9 TEA = 12.3 water = 370

The Synthesis mixture was at 149 ° C with stirring crystallized at 90 rpm for 40 to 44 hours. The obtained TEA mordenite was isolated by filtration, washed and dried, and it was found to be a crystal size according to scanning electron microscopy of <0.5 μm.

Example 2 (comparison)

According to Example 10 of US-A-4 052 472, a synthesis mixture of the following molar composition was prepared: 30 SiO ₂ , 1 Al ₂ O ₃ , 7.5 Na ₂ O, 6.3 TEA (bromide) and 310 H ₂ O TEA -Mordenitmaterial made. The synthesis mixture was crystallized (with stirring at 200 rpm) at 174 ° C for 72 hours. The TEA mordenite obtained was isolated by filtration, washed and dried, and found to have a crystal size of> 5 μm by scanning electron microscopy.

Example 3 (comparison)

TEA mordenite material was prepared according to Example 8 of US-A-3,766,093 except that sodium aluminate solution containing 25.5% Al ₂ O ₃ and 19.5% Na ₂ O was used. The synthesis mixture had the following molar composition: 30 SiO ₂ , 1 Al ₂ O ₃ , 4.4 Na ₂ O, 6.2 TEA chloride, and 310 H ₂ O, and was stirred at 171 ° C with stirring at 200 rpm for 138 hours crystallized. The obtained TEA mordenite was isolated by filtration, washed and dried, and found to have a crystal size of> 5 μm according to scanning electron microscopy.

Example 4

From the zeolite materials prepared in Examples 1 to 3 above, transalkylation catalysts were prepared by mixing each with 35% alumina binder and water and then extruding the mixture into 0.16 cm (1/16 inch) cylindrical mold. The extrudates were then precalcined in nitrogen at 540 ° C, then ion exchanged with 1N NH ₄ NO ₃ and calcined in air at 540 ° C to convert the zeolites to the hydrogen form.

A Benzene (150 g), diisopropylbenzene (50 g) and 8 g of the small-crystalline TEA mordenite prepared from Example 1 Transalkylierungskatalysators Comprehensive mixture was made in a Parr autoclave at 204 ° C, 2,170 kPa and 300 rpm for 7 hours. After 1, 3, 5 and 7 hours was taken a small sample of the product and by gas chromatography analyzed. The above test was done with those from the zeolites of the examples 2 and 3 catalysts prepared repeated. The results of three tests are summarized in Table 1, from which it can be seen is that the catalyst of the invention is significantly more effective than the previously known materials.

Table 1

Claims (10)

Process for the preparation of monoalkylated aromatic compound in which polyalkylated aromatic compound in the liquid Phase and in the presence of TEA mordenite with an average crystal size of less than 0.5 μm comprehensive Transalkylierungskatalysator with alkylierbarer aromatic Compound is brought to monoalkylated aromatic Make connection. The method of claim 1, wherein the alkyl groups the polyalkylated aromatic compound has from 1 to 5 carbon atoms have. The method of claim 1, wherein the polyalkylated selected aromatic compound is made of polyethylbenzene and polyisopropylbenzene, and the alkylatable aromatic compound is benzene. Process for the preparation of monoalkylated aromatic Compound in which: (a) alkylatable aromatic compound in the presence of alkylating catalyst with alkylating agent is brought into contact with the monoalkylated aromatic compound and to provide a product comprising polyalkylated aromatic compound, and then (b) the polyalkylated aromatic compound Step (a) in the liquid Phase and in the presence of TEA mordenite with an average Crystal size of less than 0.5 μm comprehensive transalkylation catalyst with the alkylatable aromatic Compound is brought to monoalkylated aromatic Make connection. The method of claim 4, wherein the alkylating step (a) in the liquid Phase performed becomes. The method of claim 4, wherein the alkylating agent an alkylating aliphatic group having 1 to 5 carbon atoms includes. The method of claim 4, wherein the alkylating agent Ethylene or propylene and the alkylatable aromatic compound Benzene is. The method of claim 4, wherein the alkylation catalyst selected from step (a) is from MCM-22, MCM-49, MCM-56 and zeolite β. The method of claim 4, wherein step (a) is at a temperature of 150 ° C to 316 ° C, a pressure to 20,875 kPa, a space velocity of about 0.1 to 20 WHSV (hourly mass flow rate) based on the ethylene feed, and a molar ratio of benzene to ethylene of 1: 1 to 30: 1. The method of claim 4, wherein step (b) is at a temperature of 100 to 200 ° C, a pressure of 1,000 to 5,000 kPa, an hourly mass flow rate of 1 to 10, based on total feed, and a benzene / polyalkylated Benzene-weight ratio from 1: 1 to 6: 1 becomes.